Does caffeine intake protect from Alzheimer's disease?

Caffeine is the most widely consumed behaviourally active substance in the western world. Neuroprotective effects of caffeine in low doses, chronically administered, have been shown in different experimental models. If caffeine intake could protect against neurodegeneration in Alzheimer's disease (AD), then higher levels of caffeine consumption in normal subjects as compared with AD patients should be detectable in the presumably long period before diagnosis when insidious pathogenic changes are taking place. A case-control study was used: cases were 54 patients with probable AD fulfilling the National Institute of Neurologic and Communicative Disorders and Stroke and the AD and Related Disorders Association criteria, in a Dementia Clinics setting. Controls were 54 accompanying persons, cognitively normal, matched for age (+/-3 years) and sex. Patients with AD had an average daily caffeine intake of 73.9 +/- 97.9 mg during the 20 years that preceded diagnosis of AD, whereas the controls had an average daily caffeine intake of 198.7 +/- 135.7 mg during the corresponding 20 years of their lifetimes (P < 0.001, Wilcoxon signed ranks test). Using a logistic regression model, caffeine exposure during this period was found to be significantly inversely associated with AD (odds ratio=0.40, 95% confidence interval=0.25-0.67), whereas hypertension, diabetes, stroke, head trauma, smoking habits, alcohol consumption, non-steroid anti-inflammatory drugs, vitamin E, gastric disorders, heart disease, education and family history of dementia were not statistically significantly associated with AD. Caffeine intake was associated with a significantly lower risk for AD, independently of other possible confounding variables. These results, if confirmed with future prospective studies, may have a major impact on the prevention of AD.

Evidence for free radical generation due to NADH oxidation by aldehyde oxidase during ethanol metabolism

Several studies associate ethanol hepatic toxicity to the generation of reactive oxygen species. Ethanol metabolism by alcohol dehydrogenase (ADH) originates acetaldehyde and NADH, with the subsequent increase of the NADH/NAD+ ratio. Some authors have suggested that the oxidation of acetaldehyde by aldehyde oxidase (AO) may be responsible for oxyradical generation during ethanol metabolism. In this study we demonstrated that AO acts not only upon acetaldehyde but also upon NADH, with superoxide anion radical (O2.-) formation. The apparent Km of NADH for AO was approximately 28 microM, a much smaller value than the one reported for acetaldehyde (1 mM). The NADH oxidation by AO promoted the O2.- generation and the ADP-Fe(3+)-dependent microsomal lipid peroxidation in a NADH and AO concentration-dependent manner. If in these experiments NADH is substituted by ethanol, NAD+, and ADH, a higher level of lipid peroxidation will be obtained. To explain this observation a vicious cycle which increases the oxyradical production is suggested: ADH reduces NAD+ to NADH, which is oxidized by AO, generating reactive oxidative species plus NAD+ available again for reduction by ADH. From the studies which were done in the presence of some antioxidants it was observed that the addition of SOD and/or catalase did not inhibit lipid peroxidation, but these results do not exclude the participation of reactive oxygen species. Our studies indicate that the NADH oxidation by AO may play a role in ethanol-induced generation of reactive oxygen species, contributing to its hepatotoxicity.

Pathogenicity of missense and splice site mutations in hMSH2 and hMLH1 mismatch repair genes: implications for genetic testing

BACKGROUND

In hereditary non-polyposis colorectal cancer, over 90% of the identified mutations are in two genes, hMSH2 and hMLH1. A large proportion of the mutations detected in these genes are of the missense type which may be either deleterious mutations or harmless polymorphisms.

AIM

To investigate whether nine missense and one splice site mutation of hMLH1 and hMSH2, in 10 kindreds with a familial history of colorectal cancer or young age of onset, could be interpreted as pathogenic.

METHODS

Clinical and genetic characteristics were collected: (i) evolutionary conservation of the codon involved; (ii) type of amino acid change; (iii) occurrence of mutation in healthy controls; (iv) cosegregation of mutation with disease phenotype; (v) functional consequences of gene variant; and (vi) microssatellite instability and immunoexpression of hMSH2 and hMLH1 analysis.

RESULTS

Seven different missense and one splice site mutation were identified. Only 1/8 was found in the control group, 2/7 occurred in conserved residues, and 5/7 resulted in non-conservative changes. Functional studies were available for only 2/8 mutations. Segregation of the missense variant with disease phenotype was observed in three kindreds.

CONCLUSION

In the majority of families included, there was no definitive evidence that the missense or splice site alterations were causally associated with an increased risk of developing colorectal cancer. Until further evidence is available, these mutational events should be regarded and interpreted carefully and genetic diagnosis should not be offered to these kindreds.

Detection of mutations in mismatch repair genes in Portuguese families with hereditary non-polyposis colorectal cancer (HNPCC) by a multi-method approach

Mutation searching was performed in the hMSH2 and hMLH1 genes in 20 Portuguese families representing 124 registered affected individuals. Of the 20, 16 fulfilled the classic 'Amsterdam' criteria for HNPCC, whereas the remaining four families satisfied a modified set of criteria. These criteria required a CRC diagnosed before age 50 years and cancers diagnosed in two other relatives within the HNPCC spectrum. A multi-method approach was performed using the protein truncation test (PTT), single strand conformation polymorphism (SSCP) with two different sets of conditions, heteroduplex analysis (HA) and denaturing gradient gel electrophoresis (DGGE). Putative phenotype-genotype correlations were also explored. Ten different germline mutations were identified. Six of these were found in hMLH1 in seven families and four in hMSH2 in four families. SSCP and DGGE had the highest diagnostic yields with the percentage of variants detected above 67% and together HA and PTT had the lowest. No single technique detected all variants. Trends for the absence of extracolonic manifestations were observed in families carrying hMLH1 germline mutations (four of seven in hMLH1 vs one of four in hMSH2). Most of the families with rectal cancer were associated with hMLH1 (six of seven in hMLH1 vs two of four in hMSH2). A multi-technique approach is necessary to identify a high percentage of germline mutations. Seven novel mutations were found in this Portuguese population.

Enhancement of Terbium(III)-Centered Luminescence by Tuning the Triplet Energy Level of Substituted Pyridylamino-4-R-Phenoxo Tripodal Ligands

A series of luminescent phenoxo-bridged dinuclear Tb^III complexes with tripodal ligands, 2,2'-[[(2-pyridinylmethyl)imino]di(methylene)]-bis(4-R-phenol), where R = CH₃ (L^CH3) (I), Cl (L^Cl) (II), CH₃O (L^CH3O) (III), COOCH₃ (L^COOCH3) (IV), were prepared to probe the effect of para-substitution on the phenol ring of the ligand on the Tb^III luminescence. For these Tb^III complexes a complete suppression of the ligand-centered fluorescence is observed, which demonstrates an efficient ligand-to-metal energy transfer. Complex IV was found to be the one that shows the greater intensity of the emission at room temperature. The obtained quantum yields follow the trend IV > II ≫ I > III. The quantum yield for II and IV is approximately five times greater than those obtained for I and III, indicating that the L^Cl and L^COOCH3 are better sensitizers of the Tb^III ions. These results were rationalized in terms of the variation of the energy gap between the triplet level (T₁) of the ligand and the emissive ⁵D₄ level of Tb^III, due to the electron-acceptor or electron-donor properties of the substituents. The τ_av values are in the millisecond range for all the studied complexes and resulted independent of temperature. The Commission International d'Eclairage coordinates (CIE) for all complexes are in the green color region, being insensitive to the variation of temperature. Moreover, the color purity (CP) is ca. 90% for all complexes, being ca. 100% for IV. Thus, the introduction of electron-acceptor substituents on the ligand permitted us to improve the luminescent properties of the Tb^III complexes.

A systematic study of the optical properties of mononuclear hybrid organo–inorganic lanthanoid complexes

Mononuclear organic–inorganic hybrid lanthanoid complexes show that the combination of both types of ligands improves the optical response compared to the inorganic analogue, thus having potential optical applications due to their thermal response.

Tuning White Light Emission in Dinuclear Phenoxo Bridged DyIII Complexes

A new series of dinuclear dysprosium(III) complexes, [Dy₂(L^CH₃)₂(NO₃)₂(MeOH)₂] (I), [Dy₂(L^CH₃)₂(NO₃)₂(DMF)₂]·2DMF (II), [Dy₂(L^Cl)₂(NO₃)₂(DMF)₂]·2DMF (III), and [Dy₂(L^CH₃O)₂(NO₃)₂(DMF)₂] (IV), with 2,2'-[[(2-pyridinylmethyl)imino]di(methylene)]bis(4-R-phenol), where R = CH₃, Cl, and CH₃O, were investigated as potential white light emitters. All octacoordinated dysprosium(III) are phenoxo-bridged species and have a similar coordination environment. Nevertheless, I has a MeOH ligand molecule, while for II-IV a DMF ligand replaces that of MeOH. The nature of the coordinated solvent molecule plays an important role in the behavior of the thermal dependence of the Y/B (yellow/blue) emission ratio of the Dy^III complexes (Y: ⁴F_9/2 → ⁶H_13/2, yellow and B: ⁴F_9/2 → ⁶H_15/2, blue transitions),, since for I the variation of this ratio is significant, while for the other Dy^III complexes with DMF as ligand the ratio remains constant within experimental error. At room temperature the CIE (Commission International d'Eclairage) color coordinates for the Dy^III complexes, I (0.286, 0.317), III (0.302, 0.324), and IV (0.322, 0.348) are close to the NTSC (National Television System(s) Committee) standard value for white color. Varying the temperature from 16 to 300 K the CIE coordinates for I change from the blueish to white region of the chromaticity diagram, while those of II present an inverse thermal dependence as compared to I. The CCT (Correlated Color Temperature) values at room temperature for I (8384 K), II (17235 K), and IV (5948 K) permit us to consider these complexes as candidates for white cold light emitters, the high value of II being uncommon. For I and II the CCT values vary strongly with temperature, showing a decrease with increasing temperature for I, and an increase with increasing temperature for II, thus making evident the influence on the photophysical properties of the nature of the coordinated solvent molecule in these complexes.

Europium(III), Terbium(III), and Gadolinium(III) Oxamato-Based Coordination Polymers: Visible Luminescence and Slow Magnetic Relaxation

The reaction of aqueous solutions of Eu^III, Tb^III, and Gd^III ions with Na₂Hpcpa [H₃pcpa = N-(4-carboxyphenyl)oxamic acid] afforded three new isostructural oxamate-containing lanthanide(III) coordination polymers of general formula {Ln^III₂(Hpcpa)₃(H₂O)₅·H₂O}_n [Ln = Eu (1),Tb (2), and Gd(3)]. Their structure is made up of neutral zigzag chains running parallel to the [101] direction where double syn-syn carboxylate(oxamate)-bridged dilanthanide(III) pairs (Ln1 and Ln2) are linked by three Hpcpa^2- ligands, one of them with the μ-κ²O,O':κO″ coordination mode and the other two with the μ₃-κ²O,O':κO″:κO'''. Additionally, two of those chains are interlinked through hydrogen bonding and π-π type interactions, resulting in a porous structure with channels where water molecules are hosted. The emission properties of 1 and 2 are evaluated as a function of the temperature, exhibiting an emission in red and green, respectively. The external quantum yield for 2 is approximately 7 times that obtained for 1, indicating that the oxamate ligand is a better sensitizer for Tb^III ions. The temperature dependence of the dc magnetic properties of 1-3 reveals a different magnetic behavior depending on the nature of the Ln^III ion. A continuous decrease of χ_MT occurs for 1 upon cooling, and finally χ_MT tends to vanish, as expected for the thermal depopulation of the six magnetic ⁷F_J excited states (J = 1-6) of the Eu^III ion with a nonmagnetic ⁷F₀ ground state. χ_MT for 2 decreases sharply with decreasing the temperature due to the depopulation of the splitted m_J levels of the ⁷F₇ ground state of the magnetically anisotropic Tb^III ion. A very weak antiferromagnetic interaction between the magnetically isotropic Gd^III ions across the double carboxylate(oxamate) bridge is responsible for the small decrease of χ_MT at low temperatures for 3. The dynamic (ac) magnetic properties of 2 and 3 reveal a slow magnetic relaxation with very incipient frequency-dependent χ_M″ signals below 6.0 K (2) and frequency-dependent χ_M″ peaks below 10.0 K (3) under nonzero applied dc magnetic fields, being thus new examples of field-induced single molecule magnets (SMMs).

Probing the competition between acetate and 2,2′-bipyridine ligands to bind to d-block group 12 metals

Molecular and structural diversity in Zn²⁺, Cd²⁺ and Hg²⁺ complexes towards high-efficiency luminescent materials.

The Management of Geriatric and Frail HIV Patients. A 2017 Update from the Italian Guidelines for the Use of Antiretroviral Agents and the Diagnostic Clinical Management of HIV-1 Infected Persons

OBJECTIVE

This article deals with the attempt to join HIV and geriatric care management in the 2017 edition of the Italian guidelines for the use of antiretrovirals and the diagnostic-clinical management of HIV-1 infected persons.

METHODS

The outlined recommendations are based on evidence from randomized clinical trials and observational studies published in peer-reviewed journals and/or presented at international scientific conferences in recent years. The principles of starting antiretroviral therapy in elderly patients and the viro-immunological goals are the same as in the general HIV population. However, there are some specificities to consider, related to the host as well as the therapy itself. HIV care in elderly patients must shift from a combined AntiRetroviral Therapy specific approach to a more comprehensive management, and from a disease-based model (list of co-morbidities) to a multi-morbidity and frailty standpoint. The implementation of a geriatric approach, based on the Comprehensive Geriatric Assessment, is essential and consists of a broader evaluation of health status. This multidimensional and multidisciplinary evaluation is focused on the development of a tailored intervention plan. Polypharmacy is a frequent condition in the older population and an independent risk factor for negative health-related outcomes. This can be overcome with a multidisciplinary and cooperative approach involving HIV specialists, geriatricians and primary care physicians.

CONCLUSION

The inclusion of geriatric care becomes necessary due to the novel needs of an evolving patient population. It is important to underline that the HIV specialist will continue to lead multidimensional interventions and optimize quality of care for HIV-positive people.

Enhanced Eu3+ emission in aqueous phosphotungstate colloidal systems: stabilization of polyoxometalate nanostructures

Luminescent Eu(3+)-containing polyphosphate-tungstate aqueous colloidal systems were prepared and studied as a function of the relative polyphosphate-tungstate content. In polyphosphate-rich solutions, Eu(3+) ions occupy cagelike sites composed of phosphate groups from the metaphosphate chains. In these sites, an average number of 0.5 water molecule coordinates to an Eu(3+) ion and the (5)D(0) emission quantum efficiency is 0.22. Tungstate addition leads to important modifications in neighboring Eu(3+) leading to coordination sites in the aqueous medium where metal ions are completely hidden from interactions with solvent molecules. Transmission electron microscopy results clearly show W-rich nanoparticles with sizes between 5 and 10 nm for all tungstate relative concentrations. For high tungstate relative contents (above 30 mol %), spectroscopic results suggest the presence of Eu(3+) in polyoxometalate (POM)-like sites by comparison with the well-known decatungstoeuropate [EuW(10)O(36)](9-) structure. These new aqueous colloids display surprisingly high (5)D(0) emission quantum efficiencies of ca 80% because of the strong ligand field provided by tungstate POM ligands and the complete absence of water molecules from the Eu(3+) first coordination shell.

Secondary ligands and the intramolecular hydrogen bonds drive photoluminescence quantum yields from aminopyrazine coordination polymers

Here the role of secondary ligands and their hydrogen bonding patterns in determining the photoluminescence quantum yields of aminopyrazine (ampyz) coordination polymers was probed.

Broadband NIR emission in sol-gel Er(3+)-activated SiO2-Ta2O5 glass ceramic planar and channel waveguides for optical application

An Er(3+)-doped SiO2:Ta2O5 optical channel waveguide and nanocomposite were prepared by the sol-gel route at a Si:Ta 50:50 molar ratio. Channels with an excellent surface profile were easily and quickly fabricated by focusing a femtosecond laser onto the surface of multilayered films deposited on SiO2/Si substrates. In parallel, the same sol used to prepare the film was annealed at 900, 1000, and 1100 degrees C for 2 h, to get the nanocomposite materials. A broadband NIR emission around 1538 nm, assigned to the 4I13/2 --> 4I15/2 transition of the Er3+ ions was observed in the nanocomposites of amorphous SiO2 containing dispersed Ta2O5 nanocrystals. The 4I13/2 lifetime and emission bandwidth depend on the annealing temperature. In conclusion, Er(3+)-doped SiO2:Ta2O5 channel waveguides and nanocomposites are promising materials for photonic applications.

Photoluminescence properties of Er3+ and Er3+/Yb3+ doped tellurite glass and glass-ceramics containing Bi2Te4O11 crystals

Glass and glass-ceramics containing nanocrystals of Bi₂Te₄O₁₁ cubic phase co-doped with Er³⁺ and Yb³⁺ were prepared by heat treatment of the precursor tellurite glass and investigated for optical applications. Lanthanide doped tellurite glass and glass-ceramics have been extensively investigated because of their optical and photoluminescence performance for technological photonic applications. Er³⁺ and Er³⁺/Yb³⁺ doped TeO₂-GeO₂-K₂O-Bi₂O₃ tellurite glass compositions were prepared by the conventional melt-quenching method. Photoluminescence results showed the important role played by Yb³⁺ ions when co-doping with Er³⁺ ions in comparison with the Er³⁺ single-doped glass. Due to their larger absorption cross-section, Yb³⁺ species significantly absorbs 980 nm photons and effectively transfers them to Er³⁺ ions via a set of mechanisms including ground-state absorption (GSA), excited-state absorption (ESA), and energy transfer upconversion (ETU). Er³⁺/Yb³⁺ co-doped sample was chosen for the synthesis of transparent glass-ceramics by controlled heat treatment above T_g for 5 to 120 min. X-ray diffraction patterns, high-resolution transmission electron microscopy (TEM) images, and selected area electron diffraction (SAED) from Er³⁺/Yb³⁺ co-doped glass-ceramic samples were used to verify the nanocrystal precipitation, crystalline phase, and chemical nature. The structural change resulting from the crystallization of Bi₂Te₄O₁₁ nanocrystals was evaluated by the Raman shift of the bands between 300-500 cm^-1, which are assigned to the formation of Bi-O-Te linkages and the reduction of [TeO₃] depolymerized units. The effects of HT time on the glass-ceramic's optical and upconversion photoluminescence properties were studied in the visible range under excitation at 980 nm in terms of the energy transfer mechanisms from Yb³⁺ to Er³⁺. Results indicate that Er³⁺/Yb³⁺ co-doped tellurite glass and glass-ceramics are potential candidates for photonic applications in lighting, energy conversion, and luminescent solar cell concentrators.

Phthalazine-trione as a blue-green light-emitting moiety: crystal structures, photoluminescence and theoretical calculations

Phthalazine-trione was found to be a new robust blue-green light-emitting fluorophore, regardless of the substitution pattern.

Chalcone as Potential Nonlinear Optical Material: A Combined Theoretical, Structural and Spectroscopic Study

In this work, we propose the synthesis of a novel bromine chalcone (E)-3-(2-bromophenyl)-1-(2phenylsulfonylamine)-phenyl)prop-2-en-1-one (BRC) that has been crystallized by slow evaporation technique. The second order molecular optical scattering and two-photon absorption(2PA) spectrumof the BRC molecule dissolved in Dimethyl Sulfoxide (DMSO) were evaluated by using Hyper Rayleigh Scattering and femtosecond tunable Z-Scan techniques. The first order hyperpolarizability of BRC dissolved in DMSO was estimated by using a simplified two-level model, in which one- and two-photon absorption parameters were used as input information to the model. The BRC crystal was characterized from single crystal X-ray diffraction (DRX) and spectroscopy analyzes. Also, the thermogravimetric analyses and the fluorescence spectra were obtained. In addition, an ab-initio calculation method, which includes the Møller-Plesset Perturbation Theory (MP2) and the Density Functional Theory (DFT) at CAM-B3LYP level,was used to estimate the crystal linear refractive index and the third-order electric susceptibility. Also, the average first hyperpolarizability of BRC molecules dissolved in DMSO was calculated and compared with the experimental results. The obtained values are good and qualify BRC crystal as a potential candidate for application in nonlinear optical devices.